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Old   April 7, 2003, 11:21
Default variable heat source
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I met a problem for the variable heat source. For example, the fire in the building can be taken as heat source in the simulation. But at the first stage, the heat power is: Q=a*t**2, Q is heat power, a is a constant, t is time. Only the linear heat source with time is given in software. How can I defined t-square heat source in the simulation.

Thank a lot! John
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Old   April 7, 2003, 21:50
Default Re: variable heat source
Leon Mills
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Other may have better anwser but I tend to do the following.

Q = A for t = 0 to 60sec Q = B for t = 60 to 120 sec ....

with time increments to suit you liking.

If you select the time increments appropriately and save them intheir own Q1 file it can be simple to cut and paste you fire into a new model.

Hope this helps

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Old   April 8, 2003, 02:18
Default Re: variable heat source
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Hi John,

A general form for your source can be introduced via GROUND coding, where you have access to most of the variables. This approach, however, assumes you are familiar with GROUND structure and the variable names and storage, and also can program in FORTRAN.

There are two alternatives (which I never tried myself) that are supposed to facilitate this task: PLANT and the newly introduced INFORM.

All the above is described in CHAM's site. You can also try to contact their support with your specific form of the source.

I hope this helps,

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Old   April 8, 2003, 11:12
Default Re: variable heat source
John Ludwig, CHAM
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Say the source you want is 100*t^2 W/m^3, limited to 10000 W/m^3.

To create a time-squared heat source (for the variable TEM1) using In-Form, you need to create a PATCH where you want the heat source to be. In VR-Editor, you can make a User-Defined object, and in its Attributes dialog make a new patch called, say, HEAT. Set the type to VOLUME.

In the Q1, either by hand, or using the In-Form Editor, add the lines:

inform13begin (source of tem1 at heat is min(100*tim^2,10000))


If hand-editing, save Q1 and reload working files. Run Earth. This should do it.

For more details on In-Form, look in
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